We all know how bad it is, yet still we carry on stuffing our fridges with perishable food, because we can.

After last month's courgette crisis, the UK is now in the grips of a fresh fresh vegetable panic: a shortage of iceberg lettuce, which has caused some supermarkets to impose rations. One supermarket giant is banning shoppers from buying more than three icebergs, which begs the question: who would want more than one at a time of these bland, watery lettuces?

As with courgettes, the lettuce shortage is due to the extreme cold and snow in south-eastern Spain which has killed off millions of euros worth of crops. Any that have survived are unable to reach the UK because of bad weather conditions. British consumers are posting photographs on Twitter of empty shelves where they expect their perfect, perky green veg to be all year round. As with the fuel crisis of 2000, when the UK came close to nationwide panic at petrol stations due to the mass blockading of oil refineries, there is nothing that stirs 21st century consumers more than having the everyday suddenly snatched away.

Having fresh, perfect vegetables constantly on offer, the conveyor belt always rolling, has made us carefree and lazy about where our food comes from. We no longer treasure a blemish-free, round head of calabrese as our grandparents did when they first became available in supermarkets. When a bag of mixed salad leaves is left to rot at the bottom of our fridge, we simply shrug, because there is more where that came from.

In this sense, panic is good. The current vegetable shortage is the jolt we shoppers need to appreciate our food and to stop us buying so much of it only to throw it away a week later.

Of course, it is not good for the farmers in Spain who stand to lose millions of euros from these shortages. For them, this is a genuine, livelihood-threatening crisis. For us, not being able to buy a courgette for four weeks in winter is not a crisis: it is a wake-up call.

We all know how bad it is, yet still we carry on stuffing our fridges and cupboards with perishable food because, simply, we can. It is our dirty secret, between us, the fridge and the food waste caddy

It is all too easy – and I write as someone who has an allotment – to say that the only answer to this problem is to all grow our own vegetables, or, failing that, to only eat seasonally and locally. But even with my own plot, I cannot provide for my family all year round – there is a "hungry gap" in spring when the winter vegetables finish and the broad beans and peas aren't ready. Not everyone has access to land to grow their own. When this current crisis is over, we should carry on importing vegetables from Spain. Just because we are leaving the EU, the UK cannot isolate itself from the world, and that includes doing trade with farmers from inside and outside Europe.

UK households discard £13bn worth of produce that could have been eaten

Every household loses £470 a year through avoidable food waste

Supermarkets throw away 115,000 tonnes of food every year because it is just past the sell-by date or is less than perfect

But it is quite staggering that one region in Spain, Murcia, provides 80% of Europe's vegetables during the winter months. It is simply not sustainable to be so reliant on one source of food. So we can, and should, eat more seasonally – there are plenty of UK-grown carrots, potatoes and cabbages for sale in supermarkets right now. That is only part of the solution.

The bigger lesson to learn, however, is about food waste. We all know that, as consumers, we throw away too much food: latest figures show that UK households discard £13bn worth of produce that could have been eaten. According to the government's waste agency, Wrap, some 4.4 million tonnes out of 7 million tonnes of food thrown in the bin was at some stage edible (the remainder being egg shells, chicken bones and so on). Every household loses £470 a year through avoidable food waste. These figures are not getting smaller, and we all know how bad it is, yet still we carry on stuffing our fridges and cupboards with perishable food because, simply, we can. It is our dirty secret, between us, the fridge and the food waste caddy. At the supermarket, the conveyor belt is always rolling.

Supermarkets bear some responsibility too, of course: they throw away 115,000 tonnes of food every year because it is just past the sell-by date or is less than perfect. High-profile campaigns have shamed supermarket giants into donating this food to charities have worked to an extent: Sainsbury's donated 3,000 tonnes of food last year – but this is a tiny fraction of the amount of waste they produce. Supermarkets also encourage consumers to create their own mini-waste mountains at home by three-for-two offers for food we don't actually need and won't eat.

In France, a new law was introduced last year to ban supermarkets from throwing away any unsold food, which instead is all donated to food banks and charities. There are discussions about this law being widened out to all EU countries – something that the British government can breezily disregard, now we are going to be responsible for everything, including our own rotting pile of detritus.

Brexit will change everything. The price of that perfect broccoli will rise once we're outside the customs union. It will be much harder for European hauliers to get iceberg lettuce to British supermarkets in a difficult winter. But our casual attitude to food has to stop now. If anything is going to shock us into appreciating fresh vegetables and stopping the grotesque waste of all food, it is when the conveyor belt stops.

Jane Merrick is a freelance journalist and former political editor of The Independent on Sunday. She writes an allotment blog, www.heroutdoors.uk. Follow : @janemerrick23